The fog in Custer State Park, SD persisted throughout our time there. This mother bison and her calf were across the road up on a ridge, probably less than 100 feet from us. And the dense mist hung in the air between our lenses and our subjects. It was quite a challenge to make successful photographs under these conditions. One thing that helped was to increase exposure compensation both to bring out the subjects and at the same time, still show the fog.